Process for the production of carboxylic acids



Patented May 8, 1934 UNWTEE STATES P ATENT EFF-569E PROCESS FOR THEPRODUCTIONIOF .CARBOXYLIQ ACIDS No Drawing. Application August 24, 1931,Serial No. 559,122

11 Claims.

This invention relates to the synthesis of organic compounds andparticularly to tr e preparation of hi her aliphatic acids by theinteraction of olefines, carbon monoxide, and steam.

Aliphatic acids of the higher order such as propionic acid, butyricacids, etc., have been heretoiore prepared by various methods. Forexample,;propionic acid has been obtained-by the reduction of acrylic orlactic acid; by suitable Schizomycetes fermentation of the lactate ormalate or" calcium; or by the oxidation of propyl alcohol withdichromatesolution. Such methods of preparation are necessarilyexpensive due principally to the r latively high cost of the rawmaterials. Owing to the many important uses to which acids of this typeare adaptable, many of which uses-have not been exploited extensivelydue to their present high cost,.it is obvious that a process for theirpreparation from raw materials, which are, at present, readily availableand which will be even'more readily available in the near future, willbe of far reaching importance in this art.

In my copending application Ser. No. 559,130, a

process is described for thepreparation of aliphatic oarboxylic acids ofthe higher order by the reaction of steam, carbon monoxide, and anolefinic hydrocarbon, i. e. an alpihatic hydrocarbon containing a doublebond,for example, the olefines ethylene, propylene, butylene, etc.,thesynthesis producing from these olefines propionic, butyric, and valericacidsrespectively. The acid produced contains one more carbon atom thanthe unsaturated hydrocarbon treated.

An object of the-present invention is to provide aprocess for thepreparation of aliphatic carboxylic acids from steam, carbon monoxide,and olefinic hydrocarbons. A further object of this invention is toprovide a process for the preparation of monccarboxylic acids fromsteam, carbon monoxide-and an olefine inthe presence'of a catalyst.Another object of the invention is to provide ra process for:thepreparation of acids having the structural formula RCl-I2COOH fromsteam, carbon monoxide, and an olefinic hydrocarbon, the R indicating asubstituted or unsubstituted alkyl or aralkyl grouping. Other objectsand advantages will hereinafter appear.

I have found that aliphatic carboxylic acids can be prepared from steam,carbon monoxide, and an olefinic hydrocarbon by passing these materialsin the vapor phase over a metallic halide. I prefer to use thechlorides, bromides, and iodides of the alkaline earth metals, viz.calcium, barium, and strontium, magnesium, and the alkali metals,

viz. soduim, potassium, caesium, rubidium, and

lithium, and more particularly the iodides of these elements.Other'halides which may be usedinclude the halides of tin, iron; cobalt,nickel, bismuth,-manganese, lead, titanium,-zinc, cadmium, andmolybdenum. When the last named'halides are employed-per so, however,they donot generally have as long alife as mypreferred halides of thealkali or alkaline earth elements.

Rawmaterials suitable :for usein the-process arezreadily available froma-number of sources. Thus, ethylene andxvarious homologues thereof arefound-inthergases evolved iii-cracking petroleum and may be separatedtherefrom, for

example, by fractional liquefaction. .It is;preferable, for theisake ofavoiding undesirable .byproductspthat'the hydrocarbon which it-isdesired-to convert be employedin arelatively high degree of purity.

The carbon monoxide required-for the -synthesis -may conveniently bederived 'from various commercial sources, such as, for example,watergas, producer gas, etc., by liquefaction or other methods, andshouldlikewise forthe best results be relatively pure.

Inert gases, such as nitrogen, may-'be include with the reactants, thisbeing advantageous in some cases'from' the standpoint-ofcontrolling thetemperature of the exothermic reaction and'of limiting the extentthereof, where itmay be desired to'restrict-the overall conversion ofthe reactants for the sakeoi enhancing the relative yield of thedesired" acids.

ihe relative proportions-of the reactants can be varied although it hasbeenfound that very advantageous results are obtained when the steamandcarbon monoxide areinexcess with respect to'the olefinic hydrocarbon.Concentrations of thelatter within the range oi'from 1 /2 to 5% byvolume of'thetotal reactants have been" employed with good results.

The use of pressures in excess of atmospheric, say from to-900atmospheres, is of i advantage. The reaction proceeds over a wide rangeof tem- A peratures although the optimum temperature 7 varies withspecific cases, depending inter alia upon the hydrocarbon being used.Generally the desired reaction can be obtained at from ZOO-500 C. Fromthe standpoint of practical ,105

has been found to operate satisfactorily at from 250375 C.

Catalysts suitable for the reaction may be prepared from the halides ofthe alkaline earths or the alkali metals or other elements in thefollowing manner. A solution of a halide, say approximately a 20%solution, is employed to saturate a suitable support, such, for example,as charcoal. The resulting impregnated charcoal is thoroughly dried at atemperature of approximately 120 C. after which it is ready for use as acatalyst for the reaction.

The following example will illustrate one method of practising theinvention, although the invention is not limited to the example.

Example 1.--A gaseous mixture containing parts by volume of carbonmonoxide, 5 parts by volume of ethylene, and 25 parts by volume of steamwas passed over a barium chloride catalyst which was prepared andsupported as described above in the general method for the preparationof such catalysts. The catalyst was disposed in a suitable catalyticreaction chamber capable of withstanding elevated pressure, and thepressure maintained therein at approximately 700 atmospheres and thetemperature at approximately 325 C. Upon cooling the gaseous product acondensate was obtained containing 8% of propionic acid.

Example 2.Under conditions similar to those employed in Example 1 sodiumbromide was used as the catalyst. This catalyst gave a condensatecontaining 15.3% total aliphatic carboxylic acids, predominantlypropionic.

Example 3.-A gaseous mixture containing by volume 5 parts of ethylene,95 parts of carbon monoxide with a steam to ethylene and carbon monoxideratio of 0.30 was passed over a calcium iodide catalyst under a pressureof approximately 700 atmospheres and a temperature of approximately 325C.,-'75% of the ethylene reacted to give a condensate containing 33.4%propionic acid.

The apparatus, which may be employed for conducting these reactions, maybe of any conventional type and preferably one in which the temperatureof exothermic reactions can be readily controlled at the desired value.Owing to the corrosive action of the acids produced, the interior of theconverter and conduits leading therefrom should preferably be protected.This may be accomplished by using glass or glass-lined apparatus or bycoating the inner surfaces of the apparatus with chromium or silver orusing for the construction of this equipment acid-resisting alloys of,for example, molybdenum, cobalt, tungsten, chromium, manganese, ornickel.

Various changes may be made in the method hereinbefore described withoutdeparting from the invention or sacrificing any of the advantagesthereof.

I claim:

1. In a process of reacting a gaseous mixture containing an olefinichydrocarbon, steam, and carbon monoxide and thereby producing analiphatic carboxylic acid, the step of passing the gaseous mixture overa metal halide as a catalyst for the reaction.

2. In a process of reacting a gaseous mixture containing an olefinichydrocarbon, steam, and carbon monoxide and thereby producing analiphatic carboxylic acid, the step of passing the gaseous mixture overa halide of an element selected from the group consisting of thealkaline earth and alkali metals as a catalyst for the reaction.

3. In a process of reacting a gaseous mixture containing an olefinichydrocarbon, steam, and carbon monoxide and thereby producing analiphatic carboxylic acid, the step of passing the gaseous mixture overa metal iodide as a catalyst for the reaction.

4.. In a process of reacting a gaseous mixture containing an olefinichydrocarbon, steam, and carbon monoxide and thereby producing analiphatic carboxylic acid, the step of passing the gaseous mixture overan iodide of an element selected from the group consisting of thealkaline earth and alkali metals as a catalyst for the reaction.

5. In a process of reacting a gaseous mixture containing an olefine,steam, and carbon monoxide and thereby producing an aliphatic carboxylicacid, the step of passing the gaseous mixture over a metal halide as acatalyst for the reaction.

6. In a process of reacting a gaseous mixture containing an olefine,steam, and carbon monoxide and thereby producing an aliphatic carboxylicacid, the step of passing the gaseous mixture over a metal iodide as acatalyst for the reaction.

'7. In a process of reacting a gaseous mixture containing ethylene,steam, and carbon monoxide and thereby producing propionic acid, thestep of passing the gaseous mixture over a metal halide as a catalystfor the reaction.

8. In a process of reacting a gaseous mixture containing ethylene,steam, and carbon monoxide and thereby producing propionic acid, thestep of passing the gaseous mixture over a metal iodide as a catalystfor the reaction.

9. In a process of reacting a gaseous mixture containing ethylene,steam, and carbon monoxide and thereby producing propionic acid, thestep of passing the gaseous mixture over barium chloride as a catalystfor the reaction.

10. In a process of reacting a gaseous mixture containing ethylene,steam, and carbon monoxide and thereby producing propionic acid, thestep of passing the gaseous mixture over calcium iodide as a catalystfor the reaction.

11. In a process of reacting a gaseous mixture containing ethylene,steam, and carbon monoxide and thereby producing propionic acid, thestep of passing the gaseous mixture over sodium bromide as a catalystfor the reaction.

GILBERT B. CARPENTER.

